The Experts below are selected from a list of 45216 Experts worldwide ranked by ideXlab platform
Jörgen I. Johnsson - One of the best experts on this subject based on the ideXlab platform.
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Investment in territorial defence depends on rearing environment in brown trout (Salmo trutta)
Behavioral Ecology and Sociobiology, 2003Co-Authors: L. Fredrik Sundström, Mare Lõhmus, Jörgen I. JohnssonAbstract:In many animals, territoriality will arise or cease depending on environmental factors such as intruder rate and resource availability. We investigated the effect of rearing environment on territorial behaviour in ~1.5-month-old brown trout. In the laboratory, wild-caught (reared at a low density) and Hatchery-reared (high density) trout were allowed to defend a territory against a size-matched intruder reared in the same or the other environment. Because territorial behaviour should be relaxed at high-rearing densities, we hypothesized that Hatchery-reared trout should value their territories less and therefore invest less in defence compared with wild-caught trout. However, in all cases, territory owners were more likely to win the contest and Hatchery-reared trout were just as likely as wild-reared to win mixed contests. Furthermore, pairs of Hatchery-reared trout initiated contests sooner, fought longer and were more aggressive during the contest compared with pairs of wild trout. When Hatchery-reared owners met wild intruders, the contest ended sooner compared with when the roles were reversed. We conclude that territorial behaviour in brown trout is largely innate, but that the Hatchery environment has promoted more aggressive individuals. These results suggest that Hatchery-reared trout invest more time and energy to obtain the same contest success as wild trout. In conclusion, the lack of experience of territorial defence in a high-density rearing environment seems to reduce the efficiency of territorial behaviour. In turn, this may have negative consequences for the performance of released Hatchery fish in the wild.
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density dependent growth in brown trout effects of introducing wild and Hatchery fish
Journal of Animal Ecology, 2002Co-Authors: Torgny Bohlin, Jörgen I. Johnsson, L F Sundstrom, Johan Hojesjo, J PetterssonAbstract:Summary 1 Although it is not clear to what extent density dependence acts on the survival, emigration or growth of organisms, experiments testing alternative explanations are rare. A field experiment on 1-year-old brown trout ( Salmo trutta L.) was undertaken to address the following questions: are the mortality, movement and growth of wild stream-living trout affected by population density? If so, are the density-dependent effects of released Hatchery trout different from the effects of wild fish? 2 In each of two small streams, two replicate treatment blocks were used, each with four treatments assigned to stream sections 50–70 m in length: (1) control, no fish was introduced and population density was kept at its original level. (2) Trout biomass was doubled by introducing additional wild fish. (3) Trout biomass was doubled by introducing additional Hatchery fish. (4) Hatchery trout were introduced, but biomass was kept at its original level by the removal of some resident wild fish. 3 We found no treatment effects on the recapture rates of resident trout, which suggests that survival was not strongly affected by competition. They were also remarkably stationary, regardless of treatment. However, trout growth rate was reduced to the same extent in both treatments with increased density, suggesting that growth was negatively density-dependent, and that the density-dependent effects of Hatchery trout and introduced wild fish were similar. 4 Wild resident fish grew faster than introduced wild trout, which in turn grew faster than Hatchery trout. Hatchery fish and introduced wild fish moved more than wild resident fish. 5 The results show that population density affected growth in trout parr. We conclude that competition is not limited to the underyearlings, as has previously been suggested, and that density-dependent growth is the main density-dependent response in yearling trout. Furthermore, this effect was the same for wild and Hatchery-reared competitors, suggesting that stocking of Hatchery fish may affect natural populations negatively through density dependence.
Jean-marc Roussel - One of the best experts on this subject based on the ideXlab platform.
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Coupling genetic and otolith trace element analyses to identify river-born fish with Hatchery pedigrees in stocked Atlantic salmon (Salmo salar) populations
Canadian Journal of Fisheries and Aquatic Sciences, 2011Co-Authors: Charles Perrier, Françoise Daverat, Guillaume Evanno, Christophe Pecheyran, Jean-luc Baglinière, Jean-marc RousselAbstract:This study combines otolith trace element and genetic analyses to explore the origin of individuals when Hatcheryreared fish are released into wild populations. We sampled 90 juvenile Atlantic salmon (Salmo salar) in four rivers in Normandy (France) and in the Hatchery stock. Individuals were analyzed at six microsatellite markers and their otolith elemental concentrations (14 elements) were measured using femto-second laser ablation inductively-coupled plasma mass spectrometry. Wild populations were genetically differentiated from the Hatchery strain (F(ST) approximate to 0.06). Significant differences in elemental concentrations were found among otoliths of juveniles from the four rivers and the Hatchery, allowing the identification of their geographic origin (83%-100% correct assignment). Coupling genetic and trace element analyses on the same individuals provided formal evidence that Hatchery-born juveniles released into the wild can migrate to the sea and return as adul! ts to breed on natural spawning grounds. Their progeny have pure Hatchery pedigrees but have otoliths typical of river-born juveniles, meaning that they can be mistaken for Hatchery-raised juveniles if only genetic data are considered. The presence of hybrids also confirmed that individuals with Hatchery pedigrees can breed with wild conspecifics.
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Coupling genetic and otolith trace element analyses to identify river-born fish with Hatchery pedigrees in stocked Atlantic salmon (Salmo salar) populations
Canadian Journal of Fisheries and Aquatic Sciences, 2011Co-Authors: Charles Perrier, Françoise Daverat, Guillaume Evanno, Christophe Pecheyran, Jean-luc Baglinière, Jean-marc RousselAbstract:This study combines otolith trace element and genetic analyses to explore the origin of individuals when Hatcheryreared fish are released into wild populations. We sampled 90 juvenile Atlantic salmon (Salmo salar) in four rivers in Normandy (France) and in the Hatchery stock. Individuals were analyzed at six microsatellite markers and their otolith elemental concentrations (14 elements) were measured using femto-second laser ablation inductively-coupled plasma mass spectrometry. Wild populations were genetically differentiated from the Hatchery strain (FST ≈ 0.06). Significant differences in elemental concentrations were found among otoliths of juveniles from the four rivers and the Hatchery, allowing the identification of their geographic origin (83%100% correct assignment). Coupling genetic and trace element analyses on the same individuals provided formal evidence that Hatchery-born juveniles released into the wild can migrate to the sea and return as adults to breed on natural spawning grounds. Their progeny have pure Hatchery pedigrees but have otoliths typical of riverborn juveniles, meaning that they can be mistaken for Hatchery-raised juveniles if only genetic data are considered. The presence of hybrids also confirmed that individuals with Hatchery pedigrees can breed with wild conspecifics.
Lars-ove Eriksson - One of the best experts on this subject based on the ideXlab platform.
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Migration performance of wild and Hatchery sea trout (Salmo trutta L.) smolts—Implications for compensatory Hatchery programs
Fisheries Research, 2009Co-Authors: Ignacio Serrano, Stefan Larsson, Lars-ove ErikssonAbstract:Migration success of Hatchery-reared and wild sea trout smolts through the lower stretches and the estuary of a Baltic Sea river were studied. During 3 years, wild and Hatchery trout smolts were implanted with acoustic transmitters and released 14 km upstream from the river mouth. In order to monitor their out-migration pattern, acoustic receivers were deployed along the migratory route. Data on number of fish detected and date and time of detections were analysed and the migratory performance of wild and Hatchery-reared fish was compared. A significantly higher proportion of wild fish (80%) successfully migrated to the coast compared to fish of Hatchery origin (27.5%) and migration was faster in wild smolts. Hatchery fish were larger and had a higher condition factor and lipid concentrations, which are proposed as possible reasons for the poorer migratory performance of the Hatchery-reared fish.
Karenlise Dons Mensberg - One of the best experts on this subject based on the ideXlab platform.
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microsatellite and mitochondrial dna polymorphism reveals life history dependent interbreeding between Hatchery and wild brown trout salmo trutta l
Molecular Ecology, 2000Co-Authors: Michael Moller Hansen, Daniel E Ruzzante, Einar Eg Nielsen, Karenlise Dons MensbergAbstract:The effects of stocking Hatchery trout into wild populations were studied in a Danish river, using microsatellite and mitochondrial DNA (mtDNA) markers. Baseline samples were taken from Hatchery trout and wild trout assumed to be unaffected by previous stocking. Also, samples were taken from resident and sea trout from a stocked section of the river. Genetic differentiation between the Hatchery strain and the local wild population was modest (microsatellite FST = 0.06). Using assignment tests, more than 90% of individuals from the baseline samples were classified correctly. Assignment tests involving samples from the stocked river section suggested that the contribution by Hatchery trout was low among sea trout (< 7%), but high (46%) among resident trout. Hybrid index analysis and a high percentage of mtDNA haplotypes specific to indigenous trout observed among resident trout that were assigned to the Hatchery strain suggested that interbreeding took place between Hatchery and wild trout. The latter result also indicated that male Hatchery trout contributed more to interbreeding than females. We suggest that stronger selection acts against stocked Hatchery trout that become anadromous compared to Hatchery trout that become resident. As most resident trout are males this could also explain why gene flow from Hatchery to wild trout appeared to be male biased. The results show that even despite modest differentiation at neutral loci domesticated trout may still perform worse than local populations and it is important to be aware of differential survival and reproductive success both between life-history types and between sexes.
Charles Perrier - One of the best experts on this subject based on the ideXlab platform.
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Coupling genetic and otolith trace element analyses to identify river-born fish with Hatchery pedigrees in stocked Atlantic salmon (Salmo salar) populations
Canadian Journal of Fisheries and Aquatic Sciences, 2011Co-Authors: Charles Perrier, Françoise Daverat, Guillaume Evanno, Christophe Pecheyran, Jean-luc Baglinière, Jean-marc RousselAbstract:This study combines otolith trace element and genetic analyses to explore the origin of individuals when Hatcheryreared fish are released into wild populations. We sampled 90 juvenile Atlantic salmon (Salmo salar) in four rivers in Normandy (France) and in the Hatchery stock. Individuals were analyzed at six microsatellite markers and their otolith elemental concentrations (14 elements) were measured using femto-second laser ablation inductively-coupled plasma mass spectrometry. Wild populations were genetically differentiated from the Hatchery strain (F(ST) approximate to 0.06). Significant differences in elemental concentrations were found among otoliths of juveniles from the four rivers and the Hatchery, allowing the identification of their geographic origin (83%-100% correct assignment). Coupling genetic and trace element analyses on the same individuals provided formal evidence that Hatchery-born juveniles released into the wild can migrate to the sea and return as adul! ts to breed on natural spawning grounds. Their progeny have pure Hatchery pedigrees but have otoliths typical of river-born juveniles, meaning that they can be mistaken for Hatchery-raised juveniles if only genetic data are considered. The presence of hybrids also confirmed that individuals with Hatchery pedigrees can breed with wild conspecifics.
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Coupling genetic and otolith trace element analyses to identify river-born fish with Hatchery pedigrees in stocked Atlantic salmon (Salmo salar) populations
Canadian Journal of Fisheries and Aquatic Sciences, 2011Co-Authors: Charles Perrier, Françoise Daverat, Guillaume Evanno, Christophe Pecheyran, Jean-luc Baglinière, Jean-marc RousselAbstract:This study combines otolith trace element and genetic analyses to explore the origin of individuals when Hatcheryreared fish are released into wild populations. We sampled 90 juvenile Atlantic salmon (Salmo salar) in four rivers in Normandy (France) and in the Hatchery stock. Individuals were analyzed at six microsatellite markers and their otolith elemental concentrations (14 elements) were measured using femto-second laser ablation inductively-coupled plasma mass spectrometry. Wild populations were genetically differentiated from the Hatchery strain (FST ≈ 0.06). Significant differences in elemental concentrations were found among otoliths of juveniles from the four rivers and the Hatchery, allowing the identification of their geographic origin (83%100% correct assignment). Coupling genetic and trace element analyses on the same individuals provided formal evidence that Hatchery-born juveniles released into the wild can migrate to the sea and return as adults to breed on natural spawning grounds. Their progeny have pure Hatchery pedigrees but have otoliths typical of riverborn juveniles, meaning that they can be mistaken for Hatchery-raised juveniles if only genetic data are considered. The presence of hybrids also confirmed that individuals with Hatchery pedigrees can breed with wild conspecifics.
